Public electronic document dating list

Abstract

Systems and methods are disclosed which enable the establishment of file dates and the absence of tampering, even for documents held in secrecy and those stored in uncontrolled environments, but which does not require trusting a timestamping authority or document archival service. A trusted timestamping authority (TTSA) may be used, but even if the TTSA loses credibility or a challenger refuses to acknowledge the validity of a timestamp, a date for an electronic document may still be established. Systems and methods are disclosed which enable detection of file duplication in large collections of documents, which can improve searching for documents within the large collection.

Description

TECHNICAL FIELD[0001]The invention relates generally to information assurance. More particularly, and not by way of any limitation, the present application relates to tampering detection using cryptography and also to timestamping and establishment of an asserted date for a document.BACKGROUND[0002]The ability to easily and reliably establish that a document (a computer file) has existed as of a certain date, and further that is has not been altered by tampering since that date, has been an elusive target for certain types of documents. Document types for which an easy, reliable date proof has been a particularly elusive goal include 1) documents which have been kept in secrecy since their creation, as well as 2) documents which are retained in an uncontrolled or poorly-controlled environment, such as on a website that is susceptible to easy modification and alteration by computer hackers or even the website owner.[0003]The ability to reliably date prove such documents could provide...

AI Technical Summary

Benefits of technology

[0014]Embodiments of the invention solve problems that have been previously unsolved, for example, proving the date of a document and the lack of any alteration when a challenger of a document date does not trust the timestamping provider or refuses to acknowledge the validity of a timestamp. Embodiments of the invention thus provide a surprising result that contradicts the teachings of the prior art: The need for trusting a timestamping authority can be eliminated in many situations, even when a document is stored in secrecy under the exclusive control and possession of an untrustworthy party.

[0015]Embodiments of the invention solve another problem that has been previously unsolved: An asserted date of a document, and the lack of any alteration, can be established even when a document has been stored in an uncontrolled environment. Embodiments of the invention thus provide another surprising result: Website pages stored on a website controlled by any website operator can be reliably dated at a later time, and proven to have remained unaltered, even if the website operator is untrustworthy.

[0016]Using an embodiment of the invention, any entity, for example the PTO, a search engine operator, or a litigation party, can reliably assert and prove a date that a website document was available to the public, even without the expense of maintaining an independent archival copy of the document or using either a trusted document archival service or a trusted timestamping authority (TTSA).

Problems solved by technology

For example, in a patent dispute, if one party attempted to claim earlier development of an invention, by producing documents that had been previously held confidentially as trade secrets, the other side may bring accusations of backdating the documents.

The PTO and other organizations facing similar document dating issues lack the resources to independently generate and maintain date-provable databases of all potentially valuable internet documents.

Some internet document archiving services do exist, but due to storage requirements, these databases archive only a small percentage of available documents.

Additionally, the selection of documents for retention is outside the control of most users who would later need to rely on the archive, and further, the purported dates of the archive entries can typically be questioned and contested by opponents in litigation.

A prime example of a failure by others, to solve the problem that it is currently difficult to prove the dates of documents held in secrecy, is the relatively low adoption rate of trusted timestamping solutions.

However, these have so far failed to meaningfully solve certain problems and achieve widespread adoption, because they have multiple security vulnerabilities, require multiple conditions that are uncertain to exist, and are subject to compromise at unpredictable times.

Unfortunately, this solution is expensive, due to storage and record-keeping requirements and so, as can be expected, relatively few organizations use such a service.

It also has multiple security weaknesses, including potential corruption of the services provider employees; forgery of archival records unknown to the services provider; loss of the document by fire, flood or theft; and that the services provider is out of business at the time its services are needed to verify the document date.

However, this process requires some critical assumptions and carries significant risk.

If the TTSA is corrupt, or even if it is trustworthy, but the document challenger is skeptical, then this prior art scheme will not work to convince the challenger of the document's date.

Even worse, if the TTSA's private key is ever stolen, all documents, for which the timestamps had been signed by the stolen key, lose their date provability unless some type of remedial action is taken.

Further, similar to the reliance on the document archival services provider remaining in business, if the TTSA ever ceases operations, it may be difficult to prove the date of a document.

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